Method of operating a network

ABSTRACT

A method is proposed for operating a network having at least one switch, at least two terminals, and a controller. The controller can send data to a terminal via an application protocol, the data BEING sent via data packets within the network&#39;s link layer, as is common in a conventional Ethernet network. An additional address is added to the data packets within the data link layer (1) and the switch sends the transmission to the addressed terminal via the address (2, 6). Before transmission to the addressed terminal, the address of the data packets is deleted (3). This creates a virtual automation network within an Ethernet network.

The present invention relates to a method of operating a network, inparticular an automation network.

The method is intended to be usable for integrating components of anautomation network into an existing multifunction network, for exampleinto an Ethernet network, in particular into a fieldbus network designedas an Ethernet bus.

In existing automation networks, such as SERCOS III, there is often therestriction that devices of the automation network are the sole users ofthe network. And although the automation network is also designed as anEthernet network, it is not trivial to integrate such an automationnetwork into an existing network.

These difficulties consist of restrictions, for example in terms ofnetwork topology, which make integration into other networks difficultor impossible.

A SERCOS III automation network, for example, is based on sum frametelegrams in the form of Ethernet broadcasts without VLAN tag. Ittherefore requires a specific network topology, such as ring or linetopology, with a stable subscriber sequence.

Since the maintenance of such an order cannot be guaranteed whenintegrating such nodes into an existing Ethernet network according tothe IEEE specification, such integration is difficult or impossible.

A correspondingly known communication in an automation network is known,for example, from WO 2018/215209 [U.S. Pat. No. 11,336,657]. Here, thedevices are mainly connected in a line topology and enabled bycorresponding communication through data telegrams.

In order to also provide data nodes in an automation network, forexample in order to be able to make the subscriber sequence morevariable, a method for transmitting telegrams in an automation networkis known from DE 10 2018 129 809 [US 2021/0281666]. However, thetopology that connects the devices to the automation network is alsofixed here.

Last, a further method for routing telegrams in an automation network isknown from DE 10 2019 114 309 [U.S. Pat. No. 11,411,769], where afurther diversification of nodes in the automation network is madepossible. However, even according to this reference, an arbitrarycombination of different network topologies and an integration of anautomation network in an existing network is not possible.

Thus, it is an object of the present invention to integrate anautomation network into an existing network and to facilitate the use ofmultiple network topologies that interconnect the devices or subscribersof the network.

This object is attained by the features of the main claim.

A method is thus proposed for operating a network comprising at leastone switch. The switch serves as a node in the network and can send orreceive data in all directions of the node. Furthermore, the switchincludes programmable logic that can store and use the relationships tothe other nodes in the network.

Also, the network contains at least two terminals and a controller. Thecontroller is also referred to as the master in an automation network.

According to the invention, the controller can send data to a specificterminal via an application protocol in order to control it. Theapplication protocol is implemented via the application layer of the OSInetwork model. This means that communication via the applicationprotocol is implemented in OSI layer 7.

In accordance with the specification for Internet networks, the datasent in this way is divided into data packets and sent via the network'slink layer. This means that the individual data packets are transmittedas frames within the link layer, i.e. layer 2 of the OSI model. For thispurpose, according to the invention, an additional address is added tothe data packets within the link layer so that the data packets canreach the desired destination and be addressed to it.

The switch can thereby recognize this additional address and/or ensurethe transmission to the addressed terminal by adding the address.Optionally, the controllers can also recognize and/or add the additionaladdress.

Before transmission to the addressed terminal, the additional address ofthe data packets is deleted again, so that the original data packets arerestored from the data originally sent to the terminal.

By adding the additional address and also sending the data packetswithin the link layer, a selection of the addressed network nodes can becarried out. This means that the data packet does not have to be sent toall devices by means of a broadcast command, but a preselection is made.This preselection makes it possible to implement different networktopologies connected to the switches and still ensure communication inthe automation network.

The addition of the additional address can be done by the controlleritself or by the switches used in the network. Removing the additionaladdress can then also be done by the switches or the controller.

One possibility of the additional address is the identification of acommunication relationship and assignment of a VLAN, as used for examplefrom the “Mask & Match” method (IEEE 802.1CBdb). This function firstidentifies a communication relationship between the addressed terminaland the controller or a switch and thus limits the number of addressedterminals. By assigning a VLAN, the request is then only sent to alimited part of the terminals in the network.

Another possibility for the additional addressing medium is a multicast,unicast or broadcast to only certain MAC addresses in the network. Forthis purpose, each terminal, each switch and also each controllers has afixed MAC address that is known to the switch. Accordingly, the requestcan be sent to only a limited number of terminals with a certain circleof MAC addresses. This procedure is called “active Destination MAC” andis known from IEEE 802.1CB.

As a third option of the additional address, VLAN tags can also be usedthat are assigned depending on the egress port neighbor. These VLAN tagsare also added to the data packets. This option assigns a VLAN to aspecific group of terminals and thus addresses them.

In addition to these three possibilities for the additional address, itcan also be a source address. The address of the sender (source) is usedfor this. Also, an Ether type as defined in IEEE 802.3 can be used.Furthermore, a bit mask is conceivable as an additional address that isplaced over a part of a data packet, preferably over the first bytes ofa data packet.

Last, a combination of the above methods can be used for the additionaladdress.

By these designs it is possible to create a virtual network for thecommunication in the automation part of the network that works accordingto the normal communication rules of the automation network. The realnetwork can be branched or composed of several topologies. Thecommunication protocol of the automation network then works with thevirtual network and can also only address this. This design then makesit possible to operate an automation network as part of another networkwithout having to restrict or reprogram the function of the automationnetwork.

The switches should be located at the nodes of the networks, preferablybetween the controller and the terminals. This means that differenttopologies can be interconnected in a network starting at these nodes.

The terminals of the automation networks can be connected in series, ina ring or in a line, depending on the topology. This also corresponds tothe normal function of an automation network. In principle, severalautomation networks can thus be connected together in a network by theswitches so that subscribers who do not belong to the automation networkcan also be part of the same network.

The method according to the invention includes the step of the terminalsalso responding according to the automation network and the applicationprotocol, so that the response can be sent from the terminals to thecorresponding controller. The method functions similarly to the methoddescribed above, so that here too an additional address is added to thedata packets within the link layer and the data packets are sent to theterminal, for example the controller, via the link layer. Here, too, theadditional address is deleted again before transmission to the addressedterminal.

The advantage of this method is that only the virtual network is visibleto the application protocol, thus enabling the normal applicationcommands for the automation network. The real network can be structureddifferently by the switches, so that an almost arbitrary combination ofautomation networks and normal network is possible. The combination ofdifferent topologies is also possible.

Preferably, it is suggested that controller and terminals are parts ofan automation bus. This bus is then operated as an automation networkwith Ethernet specification.

Preferably, it is proposed to configure the controller and/or the switchby a network management that is preferably software, to be able toperform the desired progression of data from a network subscriber to theterminal.

FURTHER FEATURES ARE SHOWN IN THE ATTACHED DRAWINGS Therein:

FIG. 1 is a diagram of a network according to the invention with twoswitches;

FIG. 2 is a diagram of a branched real network according to theinvention;

FIG. 3 is a diagram of a virtual network according to the invention likeFIG. 2 ;

FIG. 4 is a diagram of a branched real network according to theinvention;

FIG. 5 is a diagram of a virtual network according to the invention likeFIG. 4 ;

FIG. 6 is a diagram of a branched real network according to theinvention;

FIG. 7 is a diagram of a virtual network according to the invention likeFIG. 6 .

FIG. 1 shows a network according to the invention with three terminals20, 21, 22, two switches 30, 31 and a controller 40.

The controller and the terminals are taken from an automation network.However, the terminals 20, 21 are included in a different network strandthan the terminal 22. The terminals 20, 21 are in a line topology andthe terminal 22 in a ring topology.

There may be other network nodes located on the branches of the network,but these are not shown in this FIG. 1 .

The branches or different topologies are connected by two switches 30,31. Accordingly, the switches 30, 31 represent nodes in the network thatconnect the different branches or topologies.

If the controller 40 now wants to send data for controlling a terminalto, for example, terminal 20, corresponding data is sent to the networkvia the application protocol. The application protocol is executed inthe application layer of the OSI network model.

According to the specifications of an Ethernet network, this data is nowdivided into data packets and sent via the link layer (OSI model layer2) according to the invention.

For this purpose, an additional address is added to the data packets 1and sent. The addition can be done via the controller 40 or via theswitch 30.

The additional address defines a group of subscribers in the networkthat is then addressed. This means that not all nodes in the network areaddressed via a broadcast, as is usual in an automation network, butonly some of the nodes, for example nodes of a specific branch in thenetwork.

In the present case, an additional address is now added to the data 1 inorder to address the terminal 20. For example, the request is sent tothe subscribers 20, 21 of the upper branch of the network in FIG. 1 .Only these subscribers are addressed by the switch 30 that uses theaddress to determine which branch of the network must be addressed inorder to reach the addressed subscriber 20.

The request first reaches terminal 21 that, however, is not addressed bythe additional address and is forwarded as shown at 7 to terminal 20.Here, the address and the specific destination match, so that terminal20 accepts and converts the data.

Before reaching the terminal 20, however, the address is deletedaccording to the invention. After evaluating the address, the switch canreach the two terminals 20, 21 via a multicast without requiring theadditional address.

FIGS. 2, 4, and 6 each show possible real-world networks, each of whichincludes multiple terminals 20-25 in different branches of the network.Furthermore, the network includes switches 30, 31 and controllers 40,41.

The switches 30, 31 are at the nodes of the network and connect theindividual branches of the network. The branches in turn can be designedin different topologies.

FIGS. 3, 5 and 7 , corresponding to FIGS. 2, 4 and 6 above, show thecorresponding virtual networks as they recognize and use the parts ofthe automation network. The mode of operation corresponds in each caseto the procedure described in FIG. 1 .

FIGS. 2 to 7 thus show possible combinations of different networkbranches and topologies that would not be possible with a normal,conventional automation network. Only the switches know the real networkand can act accordingly.

As a result, it is now possible to integrate automation networks intoconventional Ethernet networks.

The present application is not limited to the previous features. Rather,further embodiments are conceivable. For example, instead of at leastone switch, a router or a server could be used. Also, more than twoswitches and/or controllers could be used.

1. A method of operating a network comprising at least one switch, atleast two terminals and one controller, the method comprising the stepsof: the controller sending data to one of the terminals via anapplication protocol as data packets within the network's data linklayer, adding an additional address within the link layer to the datapackets, and deleting the address is when the switch sends thetransmission to the addressed terminal via the address.
 2. The methodaccording to claim 1, wherein the address is formed by identifying acommunication relationship and assigning a VLAN.
 3. The method accordingto claim 1, wherein the address is formed as a multicast or broadcastaddress.
 4. The method according to claim 1, wherein the address is aVLAN tag.
 5. The method according to claim 1, wherein the address isformed as a source address.
 6. The method according to claim 1, whereinthe address is formed as an Ether type.
 7. The method according to claim1, wherein the address is formed as a bit mask over a part of the datapackets.
 8. The method according to claim 1, wherein the switch isconnected between the controller and the terminals.
 9. The methodaccording to claim 1, wherein a plurality of the terminals are connectedin series.
 10. The method according to claim 1, wherein the responses ofthe terminals are also sent via data packets within the link layer ofthe network, an additional address within the link layer is added to thedata packets, and the address is deleted before the switch sends thetransmission to the addressed terminal via the address err and beforetransmission to the addressed terminal the address of the data packetsis deleted.
 11. The method according to claim 1, wherein the terminalsare interconnected in line topology.
 12. The method according to claim1, wherein the terminals are interconnected in ring topology.
 13. Themethod according to claim 1, wherein the addition and deletion of theaddress are performed by the switch or the controller.
 14. The methodaccording to wherein the additional address is invisible to theapplication protocol.
 15. The method according to claim 1, wherein thecontroller and the terminals are parts of an automation bus.
 16. Themethod according to claim 1, further comprising the step of: configuringthe controller and/or the switch is by a network management